Tram Museum located in Dortmund Mooskamp on an old colliery railway line formerly run by the Ruhrkohle AG, R.A.G. mining company. Due to the demise in the coal industry, a section of this former standard gauge industrial railway was taken over by the tram museum. A spokesperson at the museum informed me that the use of diesel generator units are preferred as opposed to an overhead power supply from which the trams used to operate in the days of their regular service. The main reason for not installing an overhead power supply is the high risk of cable theft.
Ein Besuch beim Nahverkehrsmuseum in Dortmund-Mooskamp